1. Field
The present disclosure relates generally to manufacturing parts and, in particular, to a method and apparatus for manufacturing hardened metallic structures. Still more particularly, the present disclosure relates to a method and apparatus for manufacturing a titanium part having a desired case thickness.
2. Background
A structure formed using titanium parts may have a reduced weight as compared to a structure formed using parts comprised of other types of metals or metal alloys. For example, without limitation, titanium parts may provide an increased strength to weight advantage over steel. However, titanium parts may not have the surface hardness desired for applications that involve the rubbing of two titanium surfaces against each other. For example, without limitation, titanium surfaces may be prone to undesired effects, such as galling, scoring, and/or fretting.
These undesired effects may be prevented using a number of different methods including, without limitation, nitriding. With nitriding, nitrogen may be introduced into a portion of the titanium part through, for example, without limitation, diffusion. This introduction of nitrogen into the titanium part may produce a layer on the surface of the titanium part comprising, without limitation, titanium nitrides. This layer may be referred to as a case for the titanium part.
Currently available processes for nitriding titanium may form cases that have a depth of about 0.005 inches or less. However, with cases of these depths, the titanium parts may not be capable of carrying larger applied loads. In other words, these case depths may be too thin to allow the titanium parts to carry larger applied loads.
For example, without limitation, titanium parts may take the form of gears, bearings, shafts, rods, and/or other suitable types of parts. Applications using these parts, such as, for example, without limitation, gear or bearing applications, may result in applied loads to titanium parts that may produce surface and sub-surface stresses in the titanium part. Currently available processes of nitriding may not provide a case depth that is deep enough to prevent these undesired stresses in the case. Additionally, currently available processes of nitriding may not be able to form cases of a sufficient depth for counteracting surface contact stresses, bending stresses, sub-surface shear stresses, and/or other undesired effects.
Therefore, it would be advantageous to have a method and apparatus that takes into account one or more of the issues discussed above, as well as possibly other issues.